The aim of this study was to create a suitable method to hybridize hydroxyapatite into chitosan solution with a good dispersion of inorganic matter in the organic phase. The preparation of chitosan/hydroxyapatite composites via a membrane diffusion process was evaluated and optimized. A diffusion time of 3 days, and chitosan, calcium chloride, and disodium hydrogen phosphate with the concentrations of 1.75 % w/v, 0.20M, and 0.12M, respectively, were found to be the optimal conditions. Scanning electron microscope observations showed a cluster of needle-shaped hydroxyapatite across the composite film when synthesized with 0.2M of calcium chloride solution and 0.12M of disodium hydrogen phosphate solution, whereas hydroxyapatite was observed in larger diffuse aggregates when synthesized at a higher concentration of both solutions. Attenuated total reflection-Fourier transform infrared spectrophotometer and X-ray diffraction analyses displayed the specific peaks for the phosphate group and 2- peaks of hydroxyapatite crystals, respectively. These results indicated that hydroxyapatite can be hybridized into a chitosan solution with good dispersion through a membrane diffusion process. (c) 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1632-1638, 2013